<!DOCTYPE html>
<html lang="en">
<head>
  <!-- Required meta tags -->
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">

  <!-- Bootstrap CSS -->
  <link rel="stylesheet" href="./css/bootstrap.css">
  <style>
    .row{
      background: #000000;
      margin-bottom: 2rem;
    }
    .row div{
      background: #399;
      border:1px solid #000000;
    }

  </style>
</head>
<body>
<!--图片 -->
<div class="container">
  <div class="row">
    <div class="col"><img src="https://v4.bootcss.com/assets/img/bootstrap-stack.png" class="img-fluid" alt=""></div>
    <div class="col"><img src="https://v4.bootcss.com/assets/img/bootstrap-stack.png" class="img-fluid" alt=""></div>
    <div class="col"><img src="https://v4.bootcss.com/assets/img/bootstrap-stack.png" class="img-fluid" alt=""></div>
  </div>
  <div class="row">
  <div class="col"><img src="https://v4.bootcss.com/assets/img/bootstrap-stack.png" class="img-thumbnail" alt=""></div>
  <div class="col"><img src="https://v4.bootcss.com/assets/img/bootstrap-stack.png" class="img-thumbnail" alt=""></div>
  <div class="col"><img src="https://v4.bootcss.com/assets/img/bootstrap-stack.png" class="img-thumbnail" alt=""></div>
</div>
</div>


<!--<script src="./js/bootstrap.js"></script>-->
</body>
</html>